There are two very important reasons for minimizing the width of any gap between the ends of a plate or blanket mounted upon a cylinder of a rotary offset printing machine. The first reason is that when a gap passes through the nip between two cylinders it jars both cylinders; and the magnitude of the jar increases with the width of the gap and the speed at which the machine is running. A press operating at a rate of 1500 fpm (457 meters per minute) requires very heavy bearer construction to withstand the shock produced by a gap in a cylinder surface passing through the nip. The second reason is that when a few miles of paper web are being printed, the paper waste caused by even a small gap can add up to a very substantial amount in any long press run.
A major factor that complicates the problem of reducing the gap where an offset plate or blanket is fastened onto the cylinder is that the extremely high rotational speed of the cylinder necessitates a very strong attachment.
Because of the great importance of minimizing the gap in an offset press cylinder, a variety of different approaches to the problem have been tried by many workers in the art over a long period of years. U.S. Pat. Nos. 2,745,344; 3,058,417; 3,195,458; and 3,362,327 show various attempts to minimize the gap in an offset press cylinder. U.S. Pat. No. 948,157 shows an attempt to minimize the gap between the ends of an abrasive wrapper on a surfacing roll.